Mutual information signal communication between two communication terminals, such as portable telephones, personal computers or the like, is usually carried out through a predetermined communication network in the form of wireless system or wire system. There has been proposed a relatively new style of such a communication network by the name of mesh network.
The mesh network is different from known communication networks each constituted with a base node which functions as a central controller and a plurality of relay nodes, each of which operates under the control by the base node. In the mesh network, any node corresponding to the base node functioning as the central controller is not provided but a plurality of relay nodes are provided in such a manner that each contiguous two of the relay nodes are placed with their communication areas overlapping partially with each other so that communication paths extend in a reticulated pattern. With the mesh network, the following advantages can be obtained. For example, when a certain one of the relay nodes provided in the mesh network is put in an obstructive condition for interrupting communication temporarily, the communication is rapidly revived through another relay node provided in the mesh network. In addition, it is easy to add a new relay node to the network.
The mesh network constituted with a plurality of relay nodes wherein communication between a communication terminal and the relay node or between the relay nodes is carried out by means of wireless is named a so called wireless mesh network. With regard to the wireless mesh network, various technical improvements have been proposed. For example, with one of such technical improvements, a communication signal which is received and transmitted by each of the relay nodes provided in the wireless mesh network is changed in its signal characteristics, such as a rate of signal, a manner of modulation, a frequency band and so on, in response to the signal receiving capacity of the relay node so that the amount of information processed in a predetermined time in the wireless mesh network is increased (as disclosed in, for example, patent document 1). Further, with another technical improvement, each of the relay nodes constituting the wireless mesh network is provided with a directive antenna system and the directivity of antenna determined by the directive antenna system is selected in response to the communication carried out through the subject relay node so that the communication efficacy in the wireless mesh network is improved (as disclosed in, for example, patent document 2).
The patent document 1: U.S. Pat. No. 6,480,497
The patent document 2: U.S. Pat. No. 6,640,087